The Apple co-founder Steve Wozniak has spoken out against wearable technology, slating most smartwatches as no more than smartphone accessories that could be relegated to the same category as Bluetooth headsets.

Apple is expected to release its first smartwatch on 9 September in California, alongside a new larger iPhone. Samsung and LG released two new smartwatches this week, joining a growing number from various manufacturers.

“I feel that wearables are a hard sell,” Wozniak told technology site CNET. “They are go-betweens for your smartphone but are an extra piece and need special advantages that the smartphone doesn’t have, in my opinion.”

“If they are just a Bluetooth go-between then it could wind up in the category of Bluetooth headsets: fun to wear and show off for a day,” said Wozniak, describing the derision that Bluetooth hands free voice calling headsets suffer and their propensity to be bought and played with for a day or two before being abandoned or left for trips in the car.

‘Chance to set the direction of wearables’

Despite sales data suggesting that consumers are tiring of current feature-light, Bluetooth-based wearables, Wozniak said he would expect Apple to offer something more akin to a mobile phone.

Samsung has also just announced a Gear S smartwatch which has built-in data capability, and can be used for phone calls and messages rather than just relay notifications from a paired smartphone.

“Apple works very hard to produce exceptionally great products and doesn’t quickly release things like a wearable. So if one is introduced I expect it to have a chance to set the direction and make the product category finally viable,” Wozniak said.

Apple confirmed that it will hold its highly anticipated iPhone 6 launch event on 9 September in a specially built large auditorium at the Flint Centre in Cupertino, where there company has its headquarters.

Its invitation included the cryptic words “wish we could say more”. Apple has dropped hints in the past about what it is set to unveil with its invites, placing multiple colours on the card for new colours of iPhones, for example.

It is unknown, what the current invite hints but the event is expected to be the biggest launch in Apple’s history.